This invention relates to material used to clean magnetic heads used in video cassette recorders and players (collectively VCR's). audio tape equipment, computer floppy disk drives and other similar equipment.
Magnetic heads must operate under quite adverse conditions. Some equipment, such as audio tape decks, have stationary magnetic heads so the tape rubs against the stationary magnetic head surface. Other equipment, such as VCR's, have a rotating magnetic head so both the tape and the head move. Although the tape and the rotating surface move in the same direction, the surface speed of the magnetic head of the VCR is much greater than that of the tape so the tape and the magnetic head still rub against one another. The magnetic heads of computer floppy disk drives are positioned along a radial path while the floppy disk rotates at a high rate of speed immediately below or above it.
Magnetic heads become contaminated with the abrasive magnetic coating within a binder carried by the substrate. The substrate is commonly a plastic film in a video or audio tape, or a plastic disk in floppy disk. One way to remove the contaminants is with a cleaning tape or disk having a much more highly abrasive surface than that found on a conventional tape or floppy disk. One such cleaning tape includes a carrier film with a magnetic iron oxide bound to its surface for cleaning magnetic heads. One drawback with this type of layered cleaning tape is that being highly abrasive, it is harmful to the magnetic head it is cleaning. Also, cleaning tapes having an abrasive magnetic coating bound to a carrier film have not been found suitable for use with cleaning liquids so that cleaning using such tapes must be done dry.
Another conventional method of cleaning magnetic heads is to use a sheet of fibrous material bonded to an opaque film substrate with the cleaning occurring on the fiber side. Although this type of magnetic head cleaning tape is far less abrasive than the above discussed abrasive cleaning tapes, it also suffers from several disadvantages. Since it is a layered, as opposed to homogeneous, structure, lamination problems can exist. Using a fibrous material, special attention must be paid to the edges of the tape to insure that the edges are clean and free of stray fibers.
A third type of cleaning tape uses a strip of fabric, such as a nylon, to clean the magnetic heads and drive components. When used with a VCR. the cassette having the fabric cleaning tape is modified so that the VCR is never given an end-of-tape signal by blocking the light path which extends through a conventional cassette. (This is not required with the above two conventional cleaning tapes since they are sufficiently opaque.) This type not only suffers from the problems associated with stray fibers, the user is required to stop th VCR before the end of the cleaning tape is reached since the VCR will not recognize it.